--- old/src/cpu/aarch64/vm/jniFastGetField_aarch64.cpp	2017-02-23 13:57:08.201894304 +0100
+++ new/src/cpu/aarch64/vm/jniFastGetField_aarch64.cpp	2017-02-23 13:57:08.101895289 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2017, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -83,6 +83,8 @@
                                               // robj ^ rcounter ^ rcounter == robj
                                               // robj is address dependent on rcounter.
 
+  // If mask changes we need to ensure that the inverse is still encodable as an immediate
+  STATIC_ASSERT(JNIHandles::weak_tag_mask == 1);
   __ andr(robj, robj, ~JNIHandles::weak_tag_mask);
 
   __ ldr(robj, Address(robj, 0));             // *obj
--- old/src/cpu/arm/vm/jniFastGetField_arm.cpp	2017-02-23 13:57:08.669889694 +0100
+++ new/src/cpu/arm/vm/jniFastGetField_arm.cpp	2017-02-23 13:57:08.573890640 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -119,10 +119,12 @@
   __ ldr_s32(Rsafept_cnt, Address(Rsafepoint_counter_addr));
   __ tbnz(Rsafept_cnt, 0, slow_case);
 
-#ifndef AARCH64
-  __ bic(R1, R1, JNIHandles::weak_tag_mask);
-#else
+#ifdef AARCH64
+  // If mask changes we need to ensure that the inverse is still encodable as an immediate
+  STATIC_ASSERT(JNIHandles::weak_tag_mask == 1);
   __ andr(R1, R1, ~JNIHandles::weak_tag_mask);
+#else
+  __ bic(R1, R1, JNIHandles::weak_tag_mask);
 #endif
 
   if (os::is_MP()) {
--- old/src/cpu/sparc/vm/jniFastGetField_sparc.cpp	2017-02-23 13:57:09.161884847 +0100
+++ new/src/cpu/sparc/vm/jniFastGetField_sparc.cpp	2017-02-23 13:57:09.057885871 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
--- old/src/cpu/x86/vm/jniFastGetField_x86_32.cpp	2017-02-23 13:57:09.621880316 +0100
+++ new/src/cpu/x86/vm/jniFastGetField_x86_32.cpp	2017-02-23 13:57:09.525881261 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -86,9 +86,7 @@
   }
   __ movptr(rax, Address(rsp, 3*wordSize));  // jfieldID
 
-  const intptr_t inverted_jweak_mask = ~static_cast<intptr_t>(JNIHandles::weak_tag_mask);
-  assert(inverted_jweak_mask == -2, "Otherwise check this code");
-  __ andl(rdx, inverted_jweak_mask); // mask is subject to sign-extension
+  __ clear_jweak_tag(rdx);
 
   __ movptr(rdx, Address(rdx, 0));           // *obj
   __ shrptr (rax, 2);                         // offset
@@ -208,9 +206,7 @@
   }
   __ movptr(rsi, Address(rsp, 4*wordSize));  // jfieldID
 
-  const intptr_t inverted_jweak_mask = ~static_cast<intptr_t>(JNIHandles::weak_tag_mask);
-  assert(inverted_jweak_mask == -2, "Otherwise check this code");
-  __ andl(rdx, inverted_jweak_mask); // mask is subject to sign-extension
+  __ clear_jweak_tag(rdx);
 
   __ movptr(rdx, Address(rdx, 0));           // *obj
   __ shrptr(rsi, 2);                         // offset
@@ -302,9 +298,7 @@
   }
   __ movptr(rax, Address(rsp, 3*wordSize));  // jfieldID
 
-  const intptr_t inverted_jweak_mask = ~static_cast<intptr_t>(JNIHandles::weak_tag_mask);
-  assert(inverted_jweak_mask == -2, "Otherwise check this code");
-  __ andl(rdx, inverted_jweak_mask);         // mask is subject to sign-extension
+  __ clear_jweak_tag(rdx);
 
   __ movptr(rdx, Address(rdx, 0));           // *obj
   __ shrptr(rax, 2);                         // offset
--- old/src/cpu/x86/vm/jniFastGetField_x86_64.cpp	2017-02-23 13:57:10.081875784 +0100
+++ new/src/cpu/x86/vm/jniFastGetField_x86_64.cpp	2017-02-23 13:57:09.985876730 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -81,10 +81,7 @@
                                                 // robj is data dependent on rcounter.
   }
 
-  const intptr_t inverted_jweak_mask = ~static_cast<intptr_t>(JNIHandles::weak_tag_mask);
-  const int32_t truncated_mask = static_cast<int32_t>(inverted_jweak_mask);
-  assert(truncated_mask == -2, "Otherwise check this code");
-  __ andq(robj, truncated_mask); // mask is subject to sign-extension
+  __ clear_jweak_tag(robj);
 
   __ movptr(robj, Address(robj, 0));             // *obj
   __ mov   (roffset, c_rarg2);
@@ -185,10 +182,7 @@
                                                 // robj is data dependent on rcounter.
   }
 
-  const intptr_t inverted_jweak_mask = ~static_cast<intptr_t>(JNIHandles::weak_tag_mask);
-  const int32_t truncated_mask = static_cast<int32_t>(inverted_jweak_mask);
-  assert(truncated_mask == -2, "Otherwise check this code");
-  __ andq(robj, truncated_mask); // mask is subject to sign-extension
+  __ clear_jweak_tag(robj);
 
   __ movptr(robj, Address(robj, 0));             // *obj
   __ mov   (roffset, c_rarg2);
--- old/src/cpu/x86/vm/macroAssembler_x86.cpp	2017-02-23 13:57:10.553871135 +0100
+++ new/src/cpu/x86/vm/macroAssembler_x86.cpp	2017-02-23 13:57:10.453872120 +0100
@@ -5159,6 +5159,13 @@
   bind(done);
 }
 
+void MacroAssembler::clear_jweak_tag(Register possibly_jweak) {
+  const int32_t inverted_jweak_mask = ~static_cast<int32_t>(JNIHandles::weak_tag_mask);
+  STATIC_ASSERT(inverted_jweak_mask == -2); // otherwise check this code
+  // The inverted mask is sign-extended
+  andptr(possibly_jweak, inverted_jweak_mask);
+}
+
 //////////////////////////////////////////////////////////////////////////////////
 #if INCLUDE_ALL_GCS
 
--- old/src/cpu/x86/vm/macroAssembler_x86.hpp	2017-02-23 13:57:11.077865973 +0100
+++ new/src/cpu/x86/vm/macroAssembler_x86.hpp	2017-02-23 13:57:10.981866919 +0100
@@ -298,6 +298,7 @@
   void store_check(Register obj, Address dst);   // same as above, dst is exact store location (reg. is destroyed)
 
   void resolve_jobject(Register value, Register thread, Register tmp);
+  void clear_jweak_tag(Register possibly_jweak);
 
 #if INCLUDE_ALL_GCS
 
--- old/test/runtime/jni/CallWithJNIWeak/libCallWithJNIWeak.c	2017-02-23 13:57:11.545861363 +0100
+++ new/test/runtime/jni/CallWithJNIWeak/libCallWithJNIWeak.c	2017-02-23 13:57:11.449862309 +0100
@@ -48,12 +48,13 @@
   jfieldID id_l = (*env)->GetFieldID(env, this_class, "l", "Ljava/lang/Object;");
   jvalue v;
 
-#define CHECK(variable, expected)                                 \
-  do { if ((variable) != (expected)) {                            \
-    (*env)->ThrowNew(env, exception,  #variable" != " #expected); \
-    return;                                                       \
-  }                                                               \
-} while(0);
+#define CHECK(variable, expected)                                   \
+  do {                                                              \
+    if ((variable) != (expected)) {                                 \
+      (*env)->ThrowNew(env, exception,  #variable" != " #expected); \
+      return;                                                       \
+    }                                                               \
+  } while(0)
 
   v.i = (*env)->GetIntField(env, self, id_i);
   CHECK(v.i, 1);